Chemical contaminants (trace metals, persistent organic pollutants) in albacore tuna from western Indian and south-eastern Atlantic Oceans: Trophic influence and potential as tracers of populations

• Published in: The Science of the total environment Vol. 596-597; pp. 481 - 495
• Main Authors: Chouvelon, Tiphaine, Brach-Papa, Christophe, Auger, Dominique, Bodin, Nathalie, Bruzac, Sandrine, Crochet, Sylvette, Degroote, Maxime, Hollanda, Stephanie J., Hubert, Clarisse, Knoery, Joël, Munschy, Catherine, Puech, Alexis, Rozuel, Emmanuelle, Thomas, Bastien, West, Wendy, Bourjea, Jérôme, Nikolic, Natacha
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-10-2017; Elsevier
• Subjects: Bioaccumulation; Biodiversity and Ecology; Ecology, environment; Ecosystems; Environmental Sciences; Global Changes; Inorganic elements; Intrinsic markers; Life Sciences; Organic contaminants; Stable isotopes; Top predator; Intrinsic markers; Organic contaminants; Bioaccumulation; Inorganic elements; Stable isotopes; Top predator; mercury concentrations; organochlorine compounds; biscay northeast atlantic; feeding ecology; enhanced bioaccumulation; thunnus-alalunga; marine food webs; merluccius-merluccius; stable-isotope analysis; polychlorinated-biphenyls
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2017.04.048

Albacore tuna (Thunnus alalunga) is a highly commercial fish species harvested in the world's Oceans. Identifying the potential links between populations is one of the key tools that can improve the current management across fisheries areas. In addition to characterising populations' contamination state, chemical compounds can help refine foraging areas, individual flows and populations' structure, especially when combined with other intrinsic biogeochemical (trophic) markers such as carbon and nitrogen stable isotopes. This study investigated the bioaccumulation of seven selected trace metals – chromium, nickel, copper (Cu), zinc (Zn), cadmium (Cd), mercury (Hg) and lead – in the muscle of 443 albacore tunas, collected over two seasons and/or years in the western Indian Ocean (WIO: Reunion Island and Seychelles) and in the south-eastern Atlantic Ocean (SEAO: South Africa). The main factor that explained metal concentration variability was the geographic origin of fish, rather than the size and the sex of individuals, or the season/year of sampling. The elements Cu, Zn, Cd and Hg indicated a segregation of the geographic groups most clearly. For similar sized-individuals, tunas from SEAO had significantly higher concentrations in Cu, Zn and Cd, but lower Hg concentrations than those from WIO. Information inferred from the analysis of trophic markers (δ13C, δ15N) and selected persistent organic pollutants, as well as information on stomach contents, corroborated the geographical differences obtained by trace metals. It also highlighted the influence of trophic ecology on metal bioaccumulation. Finally, this study evidenced the potential of metals and chemical contaminants in general as tracers, by segregating groups of individuals using different food webs or habitats, to better understand spatial connectivity at the population scale. Limited flows of individuals between the SEAO and the WIO are suggested. Albacore as predatory fish also provided some information on environmental and food web chemical contamination in the different study areas.
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•443 albacore tunas were analysed for their muscle concentrations in trace metals.•Cu, Zn, Cd and Hg were the elements that most segregated the different groups.•Trophic markers and organic contaminants confirmed the segregation observed.•Differences in trace metal bioaccumulation were linked to fish trophic ecology.•Inorganic elements can trace populations exploiting different food webs.